The Administrative/Statistical Core (Core A) is responsible for the coordination of scientific activity among the various projects and cores, and for budgetary planning, data base management, tracking and statistical consultation. In addition, Core A will continue to promote the development of new analytic procedures tailored to the special problems that are encountered in the study of rare populations. Particular attention is paid to the "alpha error problem", i.e. the danger of capitalizing on chance when many different measures are taken with relatively small populations. Our solutions to this problem include (a) constraints on the level of analysis to which a strong hypothesis applies, (b) methods for aggregating multiple variables into a single robust variable, (c) constraints on the order in which hypotheses are tested, and/or constraints on the way that individual variables are used within a single complex model, and (d) a clear and fruitful separation between hypothesis testing (confirmatory analysis) and hypothesis generation (exploratory analysis). We also outline proposals for integrative analyses across the populations under study, including the construction of models that can be used to determine "goodness-of-fit" to specific population profiles.. New methods for quantifying the important notion of "double dissociation" were developed in the current funding period, and will be applied in Years 16-20, together with techniques for the quantification of developmental trajectories (including means for quantifying the notion of "deviant developmental pathways"). Because of the addition of functional magnetic resonance imaging (fMRI) project. Because of the addition of a functional magnetic resonance imaging (fMRI) project, we also outline our approach to the special analytic challenges posed by this technique, a sit relates to the complex analytic problems associated with the analysis of electrophysiological data.